#include "common/cryptohash.h"
#include "lib/stringinfo.h"
#include "libpq/libpq-be.h"
#include "libpq/sasl.h"

Include dependency graph for scram.h:

This graph shows which files directly or indirectly include this file:

Functions
char *	pg_be_scram_build_secret (const char *password)

bool	parse_scram_secret (const char secret, int iterations, pg_cryptohash_type hash_type, int key_length, char *salt, uint8 stored_key, uint8 *server_key)

bool	scram_verify_plain_password (const char username, const char password, const char *secret)

Variables
PGDLLIMPORT int	scram_sha_256_iterations

PGDLLIMPORT const pg_be_sasl_mech	pg_be_scram_mech

Function Documentation

◆ parse_scram_secret()

bool parse_scram_secret	(	const char *	secret,
		int *	iterations,
		pg_cryptohash_type *	hash_type,
		int *	key_length,
		char **	salt,
		uint8 *	stored_key,
		uint8 *	server_key
	)

Definition at line 596 of file auth-scram.c.

 {
     char       *v;
     char       *p;
     char       *scheme_str;
     char       *salt_str;
     char       *iterations_str;
     char       *storedkey_str;
     char       *serverkey_str;
     int         decoded_len;
     char       *decoded_salt_buf;
     char       *decoded_stored_buf;
     char       *decoded_server_buf;
  
     /*
      * The secret is of form:
      *
      * SCRAM-SHA-256$<iterations>:<salt>$<storedkey>:<serverkey>
      */
     v = pstrdup(secret);
     if ((scheme_str = strtok(v, "$")) == NULL)
         goto invalid_secret;
     if ((iterations_str = strtok(NULL, ":")) == NULL)
         goto invalid_secret;
     if ((salt_str = strtok(NULL, "$")) == NULL)
         goto invalid_secret;
     if ((storedkey_str = strtok(NULL, ":")) == NULL)
         goto invalid_secret;
     if ((serverkey_str = strtok(NULL, "")) == NULL)
         goto invalid_secret;
  
     /* Parse the fields */
     if (strcmp(scheme_str, "SCRAM-SHA-256") != 0)
         goto invalid_secret;
     *hash_type = PG_SHA256;
     *key_length = SCRAM_SHA_256_KEY_LEN;
  
     errno = 0;
     *iterations = strtol(iterations_str, &p, 10);
     if (*p || errno != 0)
         goto invalid_secret;
  
     /*
      * Verify that the salt is in Base64-encoded format, by decoding it,
      * although we return the encoded version to the caller.
      */
     decoded_len = pg_b64_dec_len(strlen(salt_str));
     decoded_salt_buf = palloc(decoded_len);
     decoded_len = pg_b64_decode(salt_str, strlen(salt_str),
                                 decoded_salt_buf, decoded_len);
     if (decoded_len < 0)
         goto invalid_secret;
     *salt = pstrdup(salt_str);
  
     /*
      * Decode StoredKey and ServerKey.
      */
     decoded_len = pg_b64_dec_len(strlen(storedkey_str));
     decoded_stored_buf = palloc(decoded_len);
     decoded_len = pg_b64_decode(storedkey_str, strlen(storedkey_str),
                                 decoded_stored_buf, decoded_len);
     if (decoded_len != *key_length)
         goto invalid_secret;
     memcpy(stored_key, decoded_stored_buf, *key_length);
  
     decoded_len = pg_b64_dec_len(strlen(serverkey_str));
     decoded_server_buf = palloc(decoded_len);
     decoded_len = pg_b64_decode(serverkey_str, strlen(serverkey_str),
                                 decoded_server_buf, decoded_len);
     if (decoded_len != *key_length)
         goto invalid_secret;
     memcpy(server_key, decoded_server_buf, *key_length);
  
     return true;
  
 invalid_secret:
     *salt = NULL;
     return false;
 }

References palloc(), pg_b64_dec_len(), pg_b64_decode(), PG_SHA256, pstrdup(), and SCRAM_SHA_256_KEY_LEN.

Referenced by get_password_type(), scram_init(), and scram_verify_plain_password().

◆ pg_be_scram_build_secret()

char* pg_be_scram_build_secret ( const char * password )

Definition at line 479 of file auth-scram.c.

 {
     char       *prep_password;
     pg_saslprep_rc rc;
     char        saltbuf[SCRAM_DEFAULT_SALT_LEN];
     char       *result;
     const char *errstr = NULL;
  
     /*
      * Normalize the password with SASLprep.  If that doesn't work, because
      * the password isn't valid UTF-8 or contains prohibited characters, just
      * proceed with the original password.  (See comments at top of file.)
      */
     rc = pg_saslprep(password, &prep_password);
     if (rc == SASLPREP_SUCCESS)
         password = (const char *) prep_password;
  
     /* Generate random salt */
     if (!pg_strong_random(saltbuf, SCRAM_DEFAULT_SALT_LEN))
         ereport(ERROR,
                 (errcode(ERRCODE_INTERNAL_ERROR),
                  errmsg("could not generate random salt")));
  
     result = scram_build_secret(PG_SHA256, SCRAM_SHA_256_KEY_LEN,
                                 saltbuf, SCRAM_DEFAULT_SALT_LEN,
                                 scram_sha_256_iterations, password,
                                 &errstr);
  
     if (prep_password)
         pfree(prep_password);
  
     return result;
 }

References ereport, errcode(), errmsg(), ERROR, password, pfree(), pg_saslprep(), PG_SHA256, pg_strong_random(), SASLPREP_SUCCESS, scram_build_secret(), SCRAM_DEFAULT_SALT_LEN, scram_sha_256_iterations, and SCRAM_SHA_256_KEY_LEN.

Referenced by encrypt_password().

◆ scram_verify_plain_password()

bool scram_verify_plain_password	(	const char *	username,
		const char *	password,
		const char *	secret
	)

Definition at line 519 of file auth-scram.c.

 {
     char       *encoded_salt;
     char       *salt;
     int         saltlen;
     int         iterations;
     int         key_length = 0;
     pg_cryptohash_type hash_type;
     uint8       salted_password[SCRAM_MAX_KEY_LEN];
     uint8       stored_key[SCRAM_MAX_KEY_LEN];
     uint8       server_key[SCRAM_MAX_KEY_LEN];
     uint8       computed_key[SCRAM_MAX_KEY_LEN];
     char       *prep_password;
     pg_saslprep_rc rc;
     const char *errstr = NULL;
  
     if (!parse_scram_secret(secret, &iterations, &hash_type, &key_length,
                             &encoded_salt, stored_key, server_key))
     {
         /*
          * The password looked like a SCRAM secret, but could not be parsed.
          */
         ereport(LOG,
                 (errmsg("invalid SCRAM secret for user \"%s\"", username)));
         return false;
     }
  
     saltlen = pg_b64_dec_len(strlen(encoded_salt));
     salt = palloc(saltlen);
     saltlen = pg_b64_decode(encoded_salt, strlen(encoded_salt), salt,
                             saltlen);
     if (saltlen < 0)
     {
         ereport(LOG,
                 (errmsg("invalid SCRAM secret for user \"%s\"", username)));
         return false;
     }
  
     /* Normalize the password */
     rc = pg_saslprep(password, &prep_password);
     if (rc == SASLPREP_SUCCESS)
         password = prep_password;
  
     /* Compute Server Key based on the user-supplied plaintext password */
     if (scram_SaltedPassword(password, hash_type, key_length,
                              salt, saltlen, iterations,
                              salted_password, &errstr) < 0 ||
         scram_ServerKey(salted_password, hash_type, key_length,
                         computed_key, &errstr) < 0)
     {
         elog(ERROR, "could not compute server key: %s", errstr);
     }
  
     if (prep_password)
         pfree(prep_password);
  
     /*
      * Compare the secret's Server Key with the one computed from the
      * user-supplied password.
      */
     return memcmp(computed_key, server_key, key_length) == 0;
 }